Catalytic & Enantioselective Ring Opening of Azabicyclo[1.1.0]Butyl Carbinols via N-Allylation of Strained Tertiary Amines.

Bicyclo[1.1.0]butanes (BCBs) & aza-bicyclo[1.1.0]butanes (ABBs) are characterized by significant ring strain, which allows diverse strain-release-driven efficient and atom-economical synthetic approaches to diverse valuable C(sp3)-rich novel skeletons, which are relevant to medicinal chemistry. Catalytic and asymmetric synthetic transformations are crucial in modern chemistry, enabling the efficient and selective production of chiral molecules with applications in pharmaceuticals, agrochemicals, and more. Over the last 2 years, a large number of catalytic and asymmetric strain-release-driven ring-opening transformations of BCBs have been reported to access C(sp3)-rich architecture. Despite significant advances using BCBs, catalytic asymmetric methodologies employing ABBs remain unknown. Herein, we report the enantioselective and catalytic strain release-driven ring-opening of ABB rings, which occurs via palladium-catalyzed asymmetric N-allylation followed by spirocyclization. Quantum chemical calculations shine light on the mechanism of this process.